The present invention relates to a device for connecting one end of a pipe to a member of a circuit for conveying fluid under pressure, such as another pipe, a tank, a pump, . . .
Such a connection device generally comprises a tubular endpiece secured to the member and provided with an internal annular shoulder against which the end of the pipe comes into abutment, and means for securing said end in leakproof manner within the tubular endpiece. These means comprise a claw washer mounted in the tubular endpiece and an O-ring received in the tubular endpiece between the shoulder and the claw washer.
While the pipe end is being coupled, the end of the pipe is engaged in the tubular endpiece until it comes into abutment against the annular shoulder. The claws are then pressed against the outside surface of the pipe end, and the O-ring is in close contact with the outside surface of the pipe end, thereby making the coupling leakproof. When the circuit in which the connection device is installed is itself put under pressure, the assembly clearances of the components of the connection device have the consequence in particular of the end of the pipe backing off a little under the effect of the pressure before the claws that are biting into the outside surface of the end of the pipe become wedged. Penetration of the claws into the outside surface of the pipe also causes the pipe to back off. There thus exists a gap between the end of the pipe and the annular shoulder, and also clearance between the pipe and the endpiece.
While a liquid is circulating through the coupling zone, some of the liquid runs the risk or penetrating into said gap and into the portion of this clearance defined by the sealing ring, and said liquid runs the risk of remaining constantly stagnant therein. This gap thus constitutes a liquid retention zone. With food liquids, the liquid retained in retention zones spoils and pollutes the liquid that circulates subsequently through the coupling zone. In addition, these retention zones are of relatively small dimensions which makes them particularly difficult to clear.
There thus exists a need that has not yet been resolved in convenient manner for a connection device that provides a leakproof coupling while limiting or even eliminating liquid retention zones.
To this end, the invention provides a device for connecting a pipe end to a member, the device comprising a tubular endpiece having a first end secured to the member and a second end through which the pipe end can be engaged in the endpiece, the endpiece being provided internally with an abutment against engagement of the pipe end and means for securing the pipe end in leakproof manner inside the endpiece, these means including a sealing element and means for retaining the pipe end inside the endpiece, the connection device comprising a sleeve that is elastically deformable at least in an axial direction, which sleeve has means for fixing it axially in the endpiece and, towards the first end of the endpiece, an end provided with an annular internal shoulder for coming into abutment against an end face of the pipe end so as to form the abutment against engagement of the pipe end.
Thus, the end face at the end of the pipe in the connected position bears against the annular internal shoulder of the sleeve, causing the sleeve to be lengthened elastically, thereby maintaining close contact between the annular internal shoulder and the end face at the end of the pipe. The annular internal shoulder of the sleeve forms a kind of resilient abutment on engagement of the end of the pipe in the endpiece, thereby serving firstly to make it possible to omit the internal shoulder secured to the endpiece of a prior art connection device, thereby simplifying the structure of the connection device and facilitating cleaning, and secondly to compensate for the end of the pipe backing off when the circuit is put under pressure, with this being done by means of the sleeve relaxing elastically, thereby limiting any risk of retention zones forming.
In a particular embodiment, the sleeve is arranged to form the sealing element and it preferably comprises a cylindrical internal surface adjacent to the internal shoulder for pressing against an outside surface of the end of the pipe, the diameter of the cylindrical internal surface being slightly less than the outside diameter of the end of the pipe, and/or the sleeve has an outer frustoconical surface in the vicinity of the cylindrical inner surface, the frustoconical surface tapering towards the first end of the endpiece to co-operate with an inner surface of complementary shape of the endpiece and form means for radially shrinking the cylindrical inner surface of the sleeve.
The sleeve thus performs the two functions of constituting a resilient abutment and of constituting a sealing element. The connection device is thus simple in structure and has a relatively small number of parts.